Buffer.prototype.split = Buffer.prototype.split || function (flag){
    let res = []
    let cur = 0
    let n;
    while ((n=this.indexOf(flag,cur))!=-1) { //这里注意赋值=和!=的优先级
        res.push(this.slice(cur,n))
        cur = n + flag.length
    }
    res.push(this.slice(cur))
    return res
}